Drum brakes of the kind referred to are well known in the art. The plungers forming part of the brake actuation system are intended for cooperation with the ends of a pair of opposed, pivoted brake shoes to urge the brake shoes apart and against the interior annular surface of a rotating brake drum mounted on a wheel of the vehicle. Numerous examples from the patent literature could be given; just one and a rather typical example is DE-B-23 56 075.
A well known drawback with presently known wedge brakes of the above-mentioned type is the uneven distribution of braking forces between the two brake shoes and the resulting uneven brake lining wear. Depending upon the direction of rotation of the wheel to be braked, one of the brake shoes is "leading" and the other one "trailing," the wedge-actuated brake systems of the prior art involve a "floating" wedge, resulting in lack of control of the proper distribution of the braking forces to the respective brake shoes.